Method and apparatus for communicating with an object and module used thereby

ABSTRACT

A method for communicating with an object, for example a vehicle, using a wide area paging network and a cellular mobile communication network that includes the steps of coupling a module with at least a transmitter and a receiver to the object and using the module for communicating with in combination at least three communication networks, the first one being the wide area paging network, the second one being the cellular mobile communication network and the third one being a local network using a spread spectrum modulation method.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method for communicating with an object, andto a module used by the object. The method can for instance be used forobserving and/or localizing objects.

In the first place the invention serves to localize stolen objects,particulary vehicles, such as cars and trucks.

More generally the invention is applicable for also localizing objectsother than vehicles, such as valuable pieces of art, stolen or not.

In the second place, the invention permits communicating with vehicles,for instance for deactivating or immobilizing them at the request of theowner, the official authorities, an insurance company etc. or activatingattention attracting means such as an alarm.

In the third place the method can be used for observing vehicles e.g. intoll traffic systems.

2. Discussion of Related Art

Several systems are available or will become available shortly for thesepurposes.

An overview of the systems is found in the following table 1 and can bedivided in four different types as set forth after table 1.

TABLE 1 Overview of Existing Localization and Signalization SystemsPrinciple Area of Acc. of Name Purpose Operation Mode When Origin (m)Oper. CARANGEL L GPS + GSM/MTEX A Now Netherlands 25 Europe XC REFINDERL GPS + GSM A Now Netherlands 20 Europe QUICKTRACK L Ground system A ?Australia 50 Netherlands SPY L GPS + GSM/MTEX A ? USA 25 NetherlandsMOBITRACER L GPS + GSM A 1996 Netherlands 25 Netherlands SATSTING LGPS + GSM/MTEX A Now Canada 25 Canada STARSYS L Satellite A 1997 USA& >500 worldwide France TRACKER L Ground system P Now USA  25-100(regional) NUSAFE L GPS + GSM A 1996 Germany 25 Europe ALCATEL L GPS +GSM A ? Germany 100 Europe TRAKBAK L Ground system A 1996 UK 25Netherlands & UK SATCON L Satellite A 1999 Germany 10-50 worldwide SKEYEL GPS + GSM A 1996 Germany 10-25 Europe CEL TRAK L GPS + ATF3 A 1996Ireland 10-25 Netherlands NIGHTWATCH L Ground system A 1996 UK 10 UKCLOS L GPS + GSM A ? Netherlands 10-25 Europe SERPISPACE L GPS + GSM A1996 Italy 10-25 Europe DETVOL S induction P 1997 France 15 FranceVOLBACK S induction A Now France — France FORD/MOTOROLA D Paging P 1997Belgium — Benelux SPOOKY D Paging P 1996 Belgium — Benelux

1. Signalization systems: these systems can only signal that a vehiclewith the module installed, has passed a certain beacon. The permanentlocalization of such a system is impossible. In table 1 these systemsare marked with the letter “S” in the Purpose column.

2. Localization systems: these systems permit permanent localization ofthe vehicle in which the module is installed. Most of these systems havea data link over which the localization parameters are sent to a servicecenter. These systems are active or passive.

Active systems place a call to the service center when the vehicle isthe subject of criminal intervention.

Passive systems rely on the owner of the vehicle calling the servicecenter or a help desk.

The mode of the system is indicated by either a capital “A” or “P” intable 1.

The passive systems have the disadvantage that between the moment ofcriminal intervention and the placement of the call from the ownervaluable time can get lost. In table 1 these systems are marked with theletter “L” in the Purpose column.

Such systems are described amongst others in FR 2,718,532 and “Trackingen Tracing systemen speuren gestolen auto's op” from T. A. Koopmans,periodical “Preventie”, January 1996, issue 149, The Netherlands.

3. Deactivation systems: these systems permit the owner of the vehicleonce a theft is noticed, to deactivate his car by means of a telephonecall. In table 1 these systems are marked with the letter “D” in thePurpose column.

4. Tall traffic systems: these systems allow automatic taxation ofpassing vehicles. In table 1 these systems are marked with the letter“T” in the Purpose column.

In the described localization systems, most of them make use of GPSsatellites to do an exact localization and use the Global System forMobile communications (GSM) to communicate this exact localizationtowards what can be called a service center. One disadvantage of thistype of system involves reception of the GPS satellite signal. GPSsignals are high frequency signals and are very directional in nature.This causes signals to get lost in between higher buildings andconstructions. Since they are satellite transmitted, the signals thatreach the Earth's surface are very weak and can not penetrate anymaterial.

The GPS satellites are owned and operated by the army of the UnitedStates of America. During times of crisis, the accuracy of thetransmitted signals can be made much less than the normal accuracy. Thisto prevent “the enemy” from using one's own satellites.

Since the system is being used on a fairly regular basis in severalcivilian applications, there exist plans to turn the system into asubscribed system for which Europe has to pay a certain license fee tothe USA, making future applications subject to financial consequences.

Despite the fact that the GSM network is more reliable and independentthan the GPS system, it is not being used for localization in any ofthese systems. However, its accuracy is much less when no otherlocalization parameters are available.

The price of most of the systems in table 1 is set mostly by the priceof exploitation of the communication. Even with the current GPSsituation in which reception is still free, the GSM communication cannot be switched off but is in a permanent stand by status. Since itsfunction can then be compared with a normal GSM mobile phone thesubscription fee is the same.

Furthermore, any system that uses the GSM component in a continuousstand by or active state, will generate a lot of handover protocoloverhead. Such systems are bound to fail when used in large volumessince the current GSM networks would become swamped with protocolcommunication blocking any other useful data traffic.

The systems that use proprietary data communication protocols likeMOBITEX, ATF3 and the like all depend on the roaming agreements betweenthe several network providers of these systems. These systems are mostlyrestricted to the national borders of those countries that are servicedby these operators.

Systems that make use of ground based infrastructure, like Tracker,Trakbak, Quicktrack and Nightwatch are inherently bound by the area thatis covered by the infrastructure. Mostly, these systems operate on theprinciple that the signal of several transmitters is fed into atrigonometrical algorithm that results in localization. The most obviousdisadvantages of these systems are that the area of operation is limitedand that the infrastructure and the support and maintenance of theinfrastructure is not very cost effective when operated over a largearea for a single specific application.

Another observation that can be made about the above mentioned knownsystems and also about other systems as described in U.S. Pat. No.4,651,157, U.S. Pat. No. 5,276,728, EP 87302967 and DE 43 04 094 as anexample, is that none of these systems encrypts the communication. Ifthese systems use a cellular communication network, the only encryptionis done inside the protocol of this network. No additional privacy orsafety precautions are taken.

The above mentioned systems are not aimed at integration with themultiplexed bus systems. The logical consequence of this is that thecommunication safety with other components in the vehicle is nonexisting.

U.S. Pat. No. 5,357,561 describes a method for communicating with anobject in which two networks are used, the first one being a pagingnetwork and the second one a cellular mobile communication network. Forseveral applications the use of only these two networks is notsufficiently reliable.

BRIEF SUMMARY OF THE INVENTION

The invention seeks to provide a method for communicating with or forobserving and/or localizing objects which is safe, reliable and economicand especially can be used in different applications, as for examplelocalizing stolen objects, and observing the presence of a vehicle incertain places, permitting for instance registration for paying tolls.

In accordance with the invention this object is accomplished in a methodfor communicating with an object, more particularly a vehicle, using awide area paging network and a cellular mobile communication network, bycoupling a module with at least a transmitter and a receiver to theobject and using the module for communicating with in combination, atleast three communication networks, the first one being said wide areapaging network, the second one being said cellular mobile communicationnetwork and the third one being a local network using a spread spectrummodulation method.

For communicating or observing or localizing, a signal may be sent viathe paging network to the module and a reply signal is automaticallytransmitted back via the cellular telephone network permittingobservation and/or localization.

The above mentioned communication paging network is preferably theso-called ERMES (European Radio Message System) and the cellular networkis preferably the GSM (Global System for Mobile communications) network.The spread spectrum network preferably is the CDMA (Code DivisionMultiple Acess”) network. For each network or network system there is aninterface available.

The wide area paging network is used for the bulk communication. TheERMES communication can be either very specific towards a single addressor it can be virtually broadcast to several addresses at the same time.

The cellular telephone network is used for bidirectional datacommunication towards and from the object, particularly the vehicle.

The third network comprises a receiver which is used to receive datafrom a nearby beacon in a reliable way and a transmitter which is usedto send data to a nearby receiver in a reliable way. The chipping codesof the transmitters of several systems, for instance belonging toseveral vehicles, are statistically different enough to enable areceiving beacon to recognize and differentiate the data coming fromeach receiver.

The combined use of different networks, each with a different modulationand transmission technique, allows a broad range of communicationpossibilities with for example vehicles and that for a broad range ofapplications.

The invention also concerns a module to be used by the method accordingto the invention and to be mounted on the object to communicate with or,observe, or localize the object. This module comprises interfaces withsaid three networks.

The invention will now be described by way of example and with referenceto the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a known GSM (Global System for Mobile communications)cellular network structure;

FIG. 2 shows a known TDMA (Time Division Multiple Access) and frameorganization of a 200 kMz channel;

FIG. 3 shows a known structure of a normal burst;

FIG. 4 represents schematically a system used for performing a methodfor communicating with an object using two networks;

FIG. 5 shows the difference between a conventional and a spread centrum(known Code Division multiple Access technique);

FIG. 6 shows schematically a block diagram of the complete system usedin a preferred embodiment of the method according to the invention;

FIG. 7 shows a standardized container for generic data;

FIG. 8 illustrates the encryption process from the service center to themodule of FIG. 7;

FIG. 9 illustrates the encryption process of FIG. 8 in greater detail;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred method for communicating with and/or observing and/orlocalizing objects according to the invention involves mounting, amodule, more especially a receiver-transmitter module, on the object,and using the module to communicate with three different networks, eachhaving preferably a different modulation and transmission technique.

A first network is a so-called wide area paging network, preferably theEuropean Radio Message System, called ERMES.

A second network is a cellular telephone network, preferably the GlobalSystem for Mobile communications system, called the GSM network.

First, in order to better understand the invention, a system isdescribed which uses only these two networks.

The European Radio Message System, called ERMES, is a wide area pagingstandard that was developed during the late 1980's and is established asa standard by the European Telecommunications Standardization Institute(ETSI). Recently, it has been adopted as a global standard by theInternational Telecommunications Union. Since ERMES is a comprehensivestandard that defines all interfaces with the network, it is possible tomix the components of several vendors. This will help ensure thecompetition between vendors and make the network very cost effective.

Currently, ERMES networks are in operation in France, Germany, Finlandand the Netherlands; most European paging operators plan to introduceERMES paging services this year. Currently, one vendor, Ericsson isdelivering equipment to network operators.

ERMES is a so called second generation paging network. It is areplacement for the older POCSAG systems that are currently in use.ERMES is aimed at relieving the current bandwidth bottleneck whileallowing international roaming between countries. With current POCSAGnetworks, this roaming is not ensured, making a national pager uselessin other European countries.

ERMES operates at a rate of 6250 bits per second and can use 16channels. All receiver units can listen to traffic sent out on any ofthe 16 channels. The specific channel allocation between base stationsmakes roaming possible; adjacent base stations that do not belong to thesame network will use a different set of channels. A receiver, placed inbetween these two base stations will listen to both.

Current empirical data shows that the POCSAG standard is able to support180,000 subscribers on its single channel, while ERMES is designed tohandle more then 500,000 subscribers on any of its 16 channels. This isbased on the assumption that the message equals 10 characters. Thefigures change to 36000 POCSAG subscribers and 160000 ERMES subscribersfor a message of 40 characters.

In contrast to the POCSAG paging network that operates in theneighborhood of 448 MHz, the frequency band for ERMES is fixed at 169MHz to make it a standard. The lower frequency that is used for ERMESpaging has the advantage that the signal travels in a less directed way(more omnidirectional) so that antenna direction does not influence thereception quality.

Also, the signal is less susceptible to multi-path or ghost images thatarrive at the receiver, again making the reception more robust. TheERMES signal that arrives at the receiver can be monitored for its fieldstrength. This information can again be correlated with a certaindistance from the base station. Together with the timing parameters inGSM that are also correlated with a distance from the GSM base station,the field strength information forms the backbone of the correctlocalization of an module and thus achieve the object of the invention.More information on the GSM frame timing parameters is given hereafter.

The ERMES standard is prepared to support very long messages up to 64 KBytes and to provide transparent transfer of data, thereby providing theopportunity for new applications like the present invention to bedeveloped.

The invention can fill a very specific niche in the automotivetelecommunications business that is just starting to appear. The use ofthe GSM network in the invention is one of its strongest features, aswill become clear in the next sections.

The GSM system was designed to meet the following criteria:

Low terminal and service cost

Support for international roaming

Spectral efficiency

ISDN compatibility for data communications

Support for a new range of facilities and services

The first goal is achieved again by developing a vendor neutral standardas in the case for the ERMES network. Since all equipment interfaces arefully defined, all vendor equipment can be mixed; hence competitiondrives down the prices.

The second and third citeria are achieved by using a cellular structureand assigning each cell its own channels. The general situation of twodifferent GSM networks is shown in FIG. 1. This figure shows thefollowing components: The base transceiver stations, the base stationcontrollers and the mobile services switching center.

The base transceiver stations, called BTS, form the different cells ofthe network. They consist of a transmitter and receiver combination andwork over a predefined set of frequency bands out of a total of 125bands. All adjacent cells work on a different set of frequency channelsso that there is no channel interference between these cells. Thisenables the reuse of the frequency bands in cells that do not overlap;hence the spectral efficiency.

Since the BTS's are relatively simple units, a group of BTS's iscontrolled by a base station controller called BSC. By combining severalBTS's in one logical unit, the protocol overhead that is induced by amobile terminal equipment, like for instance a GSM telephone, can bereduced. Most of the handover information is handled by the base stationcontroller without contacting the Mobile services switching center,called MSC. The handover is the procedure used when the mobile equipmentis leaving one base station covered area and traveling into anotherarea.

The MSC controls all base station controllers in its own network. I.e.in each different network, there is only one MSC. The MSC handles theupper layers of the protocol. When a mobile terminal travels from onenetwork to another, for instance from cell A to cell B, referring toFIG. 1, it will be the MSC's of both networks that arrange the handover.Also accounting information is being exchanged for billing thecommunication cost.

It is this “layering” of responsibility that make the GSM network themost flexible mobile communications network. One of the disadvantageshowever of this layering principle is that there can exist a lot ofprotocol overhead. If for instance, referring to FIG. 1, a mobileterminal equipment is traveling from point X to point Z, but is loggedon to the network, it will generate a protocol data stream ultimatelyresulting in a handover between the two MSC's, even when the terminal isnot being used. This all happens transparently for the user.

The GSM standard specifies the frequency bands of 890 MHz for the uplinkdata stream that originates from the mobile unit towards the basestation. The band from 935 MHz up to 960 MHz is used for the downlinkfrom base station towards mobile station. Each of these bands is furtherdivided into smaller frequency bands each of 200 kHz width. To achievespectral efficiency, this finite set of frequency bands is reused,referring to FIG. 1, so that the base station B will have a differentset of frequencies than base station A or C. Base station D or E,however, can operate on the same set of frequency slots as cell Btheoretically. In practice, the reuse of frequencies is not done withonly a single interspersed cell that uses another frequency set.

The finite number of available frequencies is allocated on a nationalbasis to a number of network operators. In each country, the maximumnumber of concurrent network operators is therefore fixed.

To further increase the spectral efficiency, each of the 200 kHzfrequency bands is divided further in so called time slots, thefundamental unit of which is called a burst. The fundamental unit orburst has a length of 577 microseconds. A set of 8 of these bursts isgrouped in what is called a TDMA frame. The organization of timeslotsand frames is depicted in FIG. 2. TDMA stands for Time Division MultipleAccess. It is a technique in which each transmitter is actively sendingonly a small portion of the time, during its own slot. As a result alltransmitters cooperating, are sharing the time that is available on acertain frequency, thereby virtually increasing the available bandwidth.

The TDMA frames are further combined in sets of 51 frames or 26 frames,in a multiframe structure. The total time in such a 26-frames multiframestructure is 120 milliseconds while it is 234 milliseconds in the51-frame multiframe.

Both multiframe structures are further combined in a superframe thatlasts 6.12 seconds. So 26×51-multiframes and 51×26-multiframes arecombined into a superframe. To make the picture complete, 2048 of thesesuperframes are combined into a hyperframe that lasts a total time of 3hours 28 minutes 53 seconds and 760 milliseconds after which the systemsrestarts with sequence number 0. During such a hyperframe, every TDMAframe gets assigned a unique 22 bit sequence number that makes itpossible to uniquely identify a certain TDMA frame among the 21725184possible TDMA frames.

The structure of a single normal burst is shown in FIG. 3. This normalburst consists of a total of 156.25 bits, that fall into fourcategories:

1. The start and stop sequences that span 3 bits and signal thebeginning and the end of a burst.

2. The data payload portions that carry the useful data that needs to betransmitted. The total span of both is 116 bits.

3. The training sequence that is placed in between both data payloadportions. In the GSM frequency range, there exists an unfortunatephenomenon, called multi-path signals in which the main signal,traveling from base station towards mobile equipment, is polluted withreflections or ghost images of itself, but different in phase. Theseghost images come from the fact that the main signal is reflected bybuildings and other physical objects. The training sequence is used totrain or to teach an adaptable filter to reject these ghost images fromthe received signal.

4. The guard period forms a sort of time spacer in between bursts toaccommodate a slight offset in the timing parameters. It is there tomake sure that slightly unsynchronized bursts do not collide with eachother.

It is important to notice, that this highly complex frame structure isbased on perfect timing and, requires a very good synchronization. Alltraffic that is received at a base station, from various mobileterminals that are actively transmitting or in a handover situation,needs to be synchronized in such a way that the base station can pickthe correct burst out of the frames that reach its antennae.

This requires that each mobile terminal station starts the transmissionin a precisely timed way; i.e. a mobile equipment terminal that is 15000meters away from a base station should begin transmitting 49microseconds earlier than a mobile terminal that is only 300 meters awayfrom the base station. Since radio waves travel at the speed of light,one can roughly equate 300 meters with a delay of about 1 microsecond.

The delay or timing parameters that are used during a transmission bythe mobile terminal can thus be used to correlate back towards adistance from the base station with which it is communicating. Thisfeature combined with the inherent data transmission capabilities of theGSM network form one of the backbones of the method according to theinvention.

In its most simple form a system can be provided which makes use of twocommunication networks, such as a paging network 1, particularly theabove described network and a cellular telephone network 2, particularlythe above described GSM network.

As shown in FIG. 4, the cellular telephone network 2 comprises a numberof ground stations 3 which can receive signals 4 and transmit signals 5.The network 2 can be divided into cells, each having an action radius 6smaller than the action radius 7 of the ground stations 8 of the pagingnetwork 1 transmitting signals 9.

The cellular network 2 is coupled to the classic telephone network 10.

In the object 11, e.g. a car, a module 12 is built-in, comprising areceiver 13 which can be reached over the paging network 3 and atransmitter 14 which can communicate over the network 2 and thetelephone network 10 with a service center 15.

This center 15 comprises means 16, for instance a computer, forproducing, coding and cryptographically transforming the signals 9 and10.

Code keys are used which are only known by the service center.Preferably a so-called public-key system is used for the authenticationand cryptographic transforming of the information.

When the owner of the object 11 finds out that it has disappeared, heinforms the service center 15, which transmits a coded, encrypted signal9 over the paging network 1. All modules 12 which are in use, even onobjects which are in an underground garage, receive this signal 9 anddecode it.

The module 12 in the stolen object 11 recognizes the code andinstruction is given to the transmitter 14 to communicate with theservice center 15 via the network 2 and to transmit informationpermitting the source center to localize the stolen object.

This protocol may be repeated several times at certain intervals untilconnection with the service center 15 is made.

The connection via the network 2 can be very short, e.g. limited to theso-called “hand-shake protocol”.

The information comprised in the signal 4 transmitted by the module 12may concern only the identification of the object while the localizationis performed from the receiving information of the network 2. Dependingon the ground station 3 receiving the signal 4, the action radius 6wherein the object 11 is present is known. From the strength of thesignal 4 the distance to the corresponding ground station 3 can bededuced.

The signal 4 is normally received by several ground stations 3 and theexact location may be calculated by trigonometry.

It is also possible that the signal 4 is already representative of thelocation, e.g. giving the location or data permitting calculation of thelocation e.g. by the means 16.

In this case the module 12 has to include the means to obtain suchinformation, such as detection and calculating means for determining thestrength of the received signal 9, or the strength of one or moresignals 5, or the strength of both.

From this information, the location may be determined by trigonometriccalculation in the module 12 or in the service center 15 or in acooperating unit.

The object 11, more especially a vehicle, can be provided with meanswhich calls attention to the vehicle such as a light or a sound source,or with means immobilizing the vehicle.

The means may be coupled to the module 12 and activated via arecognizable signal 9. Two such means may be activated one after theother, for instance a silent means such as a light and later a meansproducing a sound.

In another, somewhat different embodiment, only the possibility fortransmitting signals to the object 11 is provided, but not thepossibility to receive back signals, whereby the transmitted signals arethen exclusively used to activate one or more of the means for callingattention to the vehicle.

If an owner notices that his object, for instance his vehicle, has beenstolen, he contacts the service center 15, for example by phoning from apublic cell, after which the service center 15 transmits a coded signal9 to the module 12 mounted on the object, causing the activation of theattention calling means or means that deactivates the vehicle whereinthe module 12 is mounted.

If a driving vehicle is deactivated, this may be done in such way thatthis deactivation is not dangerous to traffic, and the vehicle may forinstance be slowed down progressively.

The above-mentioned embodiments may be combined and for instance signals4 may be sent back over the cellular network 2.

If the object 11 is a vehicle, the module 12 will preferably be hiddenin the coach-work. The module 12 can be provided with a security systemfor assuring that the service center 15 is automatically informed whensomeone tries to break in the module 12 or to destroy it.

The term “module” has to be interpreted in a large sense and does notmean that its components are necessarily mounted in a same compacthousing, although this is preferred. The module may also be incoporatedin a microchip.

According to the present invention, in addition to networks 1 and 2, themethod uses a third network 17, for example a local network using aspread spectrum modulation method.

This third network 17 is preferably the CDMA technique, which is similarin goal to the above described TDMA technique.

CDMA is a specific implementation of a more general technique calledspread spectrum.

Spread spectrum is a digital coding technique in which the signal istransformed or spread out so that is appears more like noise. The codingoperation increases the number of bits transmitted and expands thebandwidth that is used. Noise has a flat, uniform spectrum with nocoherent peaks and can generally be removed by filtering. The spreadsignal has a much lower power density, but the same total power.

This lower power density, spread over the expanded transmissionbandwidth, provides resistance to jamming, interference, multi-pathfading and unwanted interception.

FIG. 5 shows the difference between conventional transmitter systems anda spread spectrum transmitter system. The spread spectrum does notsuffer from crosstalk between frequency bands and the transmitted powerof a spread spectrum system can be kept below the conventional noisepower floor.

Conventional non spread spectrum systems transmit and receive on aspecific frequency band that is just wide enough to pass theinformation. By assigning different users different frequency bands andrestricting the power that modulates the signals, undesirable crosstalkand interference is kept to a minimum.

The main advantage of spread spectrum systems and CDMA systems inparticular, is that, despite the electromagnetic interference, thesignal can be manipulated to propagate fairly well, even in very noisyenvironments, like in a moving vehicle. In spread spectrum modulation, asignal's power is spread over a larger band of frequencies. This resultsin a more robust signal that is less susceptible to electrical noise andinterference from other transmitters.

In a CDMA spread spectrum system, the original data that is to be sent,is spread by means of a spreading code. I.e. each bit is chipped into apseudo noise sequence of bits. The resulting bit stream is then sent bythe transmitter over a very wide frequency band. The rationale behindthis technique is that a spread spectrum signal with a unique spreadingcode cannot create the exact spectral characteristics as another spreadcoded signal. Using the same code as the transmitter, the receiver cancorrelate and collapse the spread signal back down to the original form,while other receivers using different codes cannot.

This feature of spread spectrum makes it possible to build and operatemultiple networks in the same location. By assigning each one its ownunique spreading code, all networks can use the same frequency band, yetremain independent. The transmissions of one network appear to the otheras random noise and can be filtered out because the spreading codes donot match.

The telematica method according to the invention aims towards a singleapplication. Its purpose is to serve as a general platform for anycommunications needs. The combination of the three different networksand modulation techniques, illustrates the strength and broadapplication base that exists for this kind of system:

Transmission of very local traffic information through local CDMAtransmitter beacons.

Transmission of nation wide traffic information through the wide areapaging network ERMES.

Transmission of pan European messages through the ERMES network.

Toll information that is distributed through local CDMA beacons.

Messages to very specific automobiles about technical control issuese.g. yearly checkup of the condition of the automobile.

Fleet control information.

Transmission of area information that can alter the regime of the enginein for instance a city traffic environment.

Immobilization of a vehicle by police forces or at the demand ofinsurance companies is also possible, but this does not always requirethe combined use of all three networks.

In FIG. 6 the overall view of the telematica system for applying themethod of the invention starting from the service center down to thereceiving module in the vehicle is represented.

The method uses a system built out of the following components:

The service center 15 from which all activity is monitored andinitiated.

The wide area paging network 1 ERMES and the cellular GSM network 2 asit is exploited by a network operator.

A third network 17 formed by local sending and receiving beacons,operating by means of the CDMA spread spectrum technique.

A module 12, located in the vehicle, that interprets all the datareceived over any of the three reception circuits. The details of thispart are described hereafter.

The responsibility of the service center 15 can be categorized in twomain objectives:

1. It will form the interface between the network operator. As such, itwill interpret all incoming and outgoing data. This is the technicalinterface.

2. It will form the high level application interface to the differentuser groups and organizations or customers of the method. This is whatcan be called the customer interface.

The technical interface of the service center 15 is responsible forcoordinating the data stream that is generated over the threecommunication networks 1, 2 and 17. This data stream is subject to ageneric protocol that offers both flexibility towards and applicationand is safe; i.e. the protocol offers genericity, encryption, decryptionand authentication.

It is clear that for an error free and safe transmission, a genericprotocol needs to be conceived. Beside the fact that the protocol willdefine a standardized container for generic data, as shown in FIG. 7, itwill perform two major tasks:

As a first task, the protocol will encrypt and authenticate any outgoingdata. The authentication can be performed by means of a public andprivate key algorithm of which the private key is in the possession ofthe service center and the public key is contained in the Read OnlyMemory (ROM) portion of the receiving module. The container, as shown inFIG. 7, carries a seed number for the random number generator in themodule. The outcome of the random number generator is the key with whichthe data can be decrypted. When the decryption is performed, theauthentication of the data can proceed by means of the public key thatis contained in the ROM of the module. This situation is described inFIG. 8.

FIG. 8 shows the following components, both on the module 12 side as onthe service center 15 side:

The random number generators (RNG's) which are initialized with a seednumber that is transmitted as clear text (unencrypted) from the servicecenter to the module.

The coefficients for these RNG's which are stored in volatile RandomAccess Memory (RAM). By using volatile RAM, the system can be made suchthat the RAM contents are destroyed when a criminal intervention istaking place.

Since on both the service center side and on the module side, the samerandom seed and RNG coefficients are being used, the data that isencrypted at the service center can be decrypted again in the module.Since volatile RNG coefficients are used, these can be changed whennecessary by the service center. The new RNG coefficients can be sentencrypted to the module and can take effect when decrypted andauthenticated.

To guarantee the uniqueness of the datapacket and hence the uniquenessof the digital signature, the contained data is interspersed withrandomly set bits, as is shown in FIG. 7.

The data stream from the service center 15 to the module 12 is digitallysigned in the center and verified for authentication in the module 12.This process is shown between the two points marked with a “Z” and an“X” in FIG. 8. The right side of the air time interface (dotted line)represents the service center 15, the left side the module 12. In FIG. 9the situation is explained in more detail, together with the encryptionthat is taking place when data is sent from the module 12 to the center15.

The encryption and authentication described in FIG. 9 is based on a socalled public key system. This means that there exists two differentkeys which are associated with each other, a public key and a privatekey. When the direction of the data stream is from service center to themodule, the data can be signed by means of the private key, i.e. adigital signature consisting of 128 bits is added to the data packetthat is shown in FIG. 7. The correctness of this signature can bevalidated only with the public key from the module 12. It is impossibleto create a digital signature with the public key. The public key canonly do a verification. Forgery of a signature is therefore virtuallyimpossible. Since we can only do an authentication of the data, theencryption system described in FIG. 8 is added on top of theauthentication.

When the direction of the data stream is from module 12 towards theservice center 15, the data that is to be sent can be encrypted by meansof the public key. The decryption can only be performed by means of theprivate key from the service center 15. A public key can never be usedto decrypt a message.

Since the authentication is performed by means of a public keyalgorithm, there is no problem when the key portion, contained in theROM of the module is ever compromized. This key can be publicly known toeveryone; it can not be used to forge any signature or to decrypt amessage.

As second task, the protocol will decrypt incoming data. In the casethat data is being received by the service center 15, the data payloadis encrypted by means of the public key in the module 12. Thisguarantees that any sensitive data that is sent back to the servicecenter 15 will only be readable by the service center 15.

As mentioned herebefore, the service center 12 will be responsible forthe coordination between the data that is generated by the threedifferent network interfaces. The CDMA data is being transported to theservice center 12 over either a fixed link or over the GSM network.Logically speaking however, there are three different data streams forthe service center to monitor.

Each different network type 1, 2 and 17 performs a very specific task ina method of the invention.

The ERMES paging network is especially suited to transport large blocksof data, up to 65 K Byte blocks. Therefore is used for bulk transport tothe module. ERMES can address a very specific module but can also beused to “broadcast” data so that all modules receive the same message.

A paging network is more robust in transmitting data. A single basestation can cover a much broader area then for instance a GSM basestation. The reception of a paging signal through concrete walls e.g.parking lots, is much better than for the rather fragile GSM signal.

A paging receiver, does not cause any protocol overhead even when it isin standby mode, listening to messages. It therefore does not consumeany bandwidth, which has its repercussions on the price of exploitation.Compared to a GSM terminal, the cost is very small.

So for both price and reliability reasons the downlink connection to themodule will be done via the ERMES paging network.

The GSM network has two very specific purposes: it provides the datauplink from module 12 to the service center 15 and it provides theservice center 15 with parameters that will allow a localization of themodule 12.

The local CDMA network 17 or beacons provide a robust communicationchannel for short messages. The main purpose of CDMA based beacons is tocommunicate toll information to all modules that pass nearby. The CDMAtransmissions towards the modules always operate in “broadcast” mode. Inthe module 12, there is also a CDMA based transmitter 18, that can sendmessages to a nearby beacon. For this transmission to succeed, even inthe possible presence of several other modules transmitting theirinformation to the same beacon, each module should use a differentbinary key so that the receiving beacon can distinguish eachtransmitter.

The CDMA based transmitters 18 and receivers 19 communicate with theservice center 15 possibly over a GSM link or a fixed link, according tothe infrastructure at hand. For fixed CDMA transmitter and receivercombinations, it is best to use a fixed link over the existing signalinginfrastructure. For mobile CDMA transmitter stations, as used intemporary situations, a GSM based link is most suited. The coordinationbetween these CDMA transmitter and receiver combinations and the GSMnetwork 2 is also performed by the service center 15.

Since from a network operator point of view, the ERMES and GSM networksare completely separated, there is a need to coordinate the traffic overboth networks. For instance, when a certain data packet is sent to themodule over the ERMES paging network and when this specific packetrequires the module to send data back, the data that is combing backover the GSM network needs to be monitored for this specificconfirmation message. If such a message is not received within a certainperiod, either the reception at module failed or the module is unable totransmit the confirmation.

In either case, the data needs to be resent by the service center 15 tothe module 12 up to the point where a confirmation message is receivedover the GSM network. If such a confirmation message is not receivedeven after a certain number of retransmissions, the module can beassumed to be faulty and the owner of the car can be contacted to checkout the situation.

The same method of repeated attempts to retransmit a data packet isbeing used at the module side.

The combined result of this coordinated retransmission protocol is ahigh communication reliability even in the presence of insufficientcoverage of either the ERMES or the GSM network.

Any data that is being transmitted and received by the service center 15will be logged for possible future reference.

In case that a localization of a module 12 is required, the servicecenter 15 will correlate the different parameters and perform thelocalization as accurately as possible. The following parameters for alocalization are available:

the TDMA frame timing parameters of the GSM network in the module,

the identity and the field strength of the ERMES base station at themodule 12. For this purpose a database that relates the identity andfield strength with a global position, has to be set up,

the correlation between both above parameters and an electronic versionof a road map, describing the situation in the neighborhood of the GSMbase station involved,

the trend of change of the first three parameters described.

The telematica module 12 according to the invention, as it is shown inFIG. 6 comprises the following blocks:

An ERMES interface 20 that receives packets of data from over the widearea paging network 1.

A GSM interface 21 that is capable of both sending and receiving digitaldata. The interface does not contain any speech encoding or decodingcircuits.

A CDMA interface 19 capable of receiving information that is broadcastin a very local area, e.g. toll information.

A CDMA interface 18 capable of sending information back to a receiverlocated nearby the vehicle at the moment of transmission.

A system that combines and controls all these interfaces by means ofsoftware and hardware, the control module 22 comprising a processor.This control module 22 also forms the peripheral interface with thevehicle, the read only memory 23 and the data storage memory 24. It canbe subdivided in several sub parts, as will be illustrated in later.

From the FIG. 6 it is clear that four different RF or radio frequencyinterfaces can be distinguished. It is clear that the electro magneticcompatibility between all four interfaces will form a complex designproblem that needs to be solved during the engineering of the module 12.

During normal operation, the most problematic RF interface is the onethat concerns protocol overhead and electromagnetic fragility. This isaddressed by switching off the GSM circuits to ensure that duringstandby operation, there will be no RF interference or electromagneticcompatibility problems caused by the GSM RF circuit. Furthermore it willguarantee the absolute privacy of the object 11 or vehicle during normalconditions. There is no tracking possible when the GSM system isswitched off.

Second, it will guarantee that there is no protocol overhead or handoveroverhead caused by a module 12 of the invention that travels through GSMbase station cells. In fact, the activation of the GSM circuits is undercontrol of either the service center 15 or the software contained in themodule 12. Since this software is also controlled by the service center,the ultimate responsibility of the GSM activity is under completesupervision of the control center.

Should the GSM circuits be activated for data transmission or forlocalization purposes, the ERMES RF interface will first be switched offbefore the GSM circuits are switched on to attempt the transmission.Again, this procedure under control of the software in the module 12will ensure the least problems regarding electro magnetic compatibility.

The CDMA network 17 or technique has already been described as beingvery resistant to jamming by conventional radio transmitter systems.Current plans are to preliminarily operate the CDMA links over a 2.4 GHz radio link and as such the interference problem with lowerfrequencies will be small.

The main purpose of the control module 22 is to glue together thedifferent network interfaces and to form the peripheral interface withthe signals as they are used in the vehicle itself. Its functions can besummed up as follows:

It forms the logical interface with the protocol layer of the servicecenter 15.

It will execute the program contained in the ROM 23 and RAM 24 part ofthe module 12 and act according to the received commands and data. It isduring the execution of this program that the module 22 will eventuallycommunicate with the object 11 or vehicle.

It will control the power on and off cycles of the different networkinterface circuits according to the commands received and the containedsoftware program to reduce interference problems as much as possible.

The first logical part of the control module 22 is the interface withthe protocol as it is used in the service center 15. When data isreceived from the service center over any of the three receiving networkinterfaces 18-19, 20 and 21, it is first necessary to check the digitalsignature of the received packet and if that proves to be authentic, thedata needs to be decrypted, as was already shown in FIG. 8.

When data is being sent to the service center 15 over either the GSMlink or over the CDMA transmitter link, the data is first encrypted withthe public key contained in the ROM 23 of the module 12, prior to beingsubmitted to the interface. All of the above functions need to beperformed in hardware by means of the protocol interface.

The processor 25 including in the control module 22 will control thecomplete module 12 and network interfaces, based upon the software thatis contained for the most part in the ROM 23 and partly in the RAM 24.The RAM portion of the software can be updated if needed by means of oneof the receiving network interfaces. This will allow a flexibleenvironment in which part of the functionality of the module 12 can bechanged during operation.

The RAM 24 that is being used to store a part of the software is dividedinto three redundant areas. This will eliminate the possibility of softand hard faults in in the RAM due to heavy particle impact, electromigration, breakdown, etc. The custom hardware in the module 12 willcheck the consistency of the data in the three different RAM areas andwill signal any malfunction back to the service center 15, if possible.

To control any errors in the processor 25 itself, a suitable built-inself test software function is run periodically and will report anyerrors back to the service center 15 if possible. Even when reportingthis situation back is impossible, the module 12 will disable itself forany further reception of critical commands.

The functionality of the embedded software and the ability to downloadnew software parts on the fly, will create new possibilities forupgrading the module 12 and offering extra services.

The control module 22 also forms the interface with the electricalsystems of the vehicle it is built-in. This peripheral interfacepresents itself in two forms:

1. The digital input and output over the multiplexed bus.

2. Analog input and output signals for which the digital equivalentsignal is not available on the multiplexed bus.

Nowadays, there is a trend in the automotive industry to standardizearound a common protocol and hardware system to convey signals in avehicle, called a multiplexed bus. This bus will enable greatercompatibility between electrical products for vehicles and will create abig reduction in the amount of wiring. The first advantage of theuniform bus structure for this application is that engineering effort tocreate the interface needs not to be repeated for every make of car.

The second advantage of the multiplexed bus is that in cooperation withthe car manufacturers a protocol can be conceived that will make itvirtually impossible to remove the module 12 from the car. The centralprocessing unit that controls the complete car can poll thetelecommunications module for its presence and eventually deactivate thecar in a safe way, when such module is absent. To prevent criminalintervention during this communication between the car's centralprocessing unit and the telecommunications module 12, the exact data canagain be encrypted by means of a temporary key, exchanged between themodule 12 and the central processing unit.

This key exchange can be made completely safe by means of a public keyalgorithm as described in “The First Ten Years of Public-KeyCryptography, Diffie, Whitfield, Proceedings of the IEEE 76.(1988) pages560-576. The main characteristic of this algorithm is that thecommunication between both modules may be monitored and intercepted, andyet it is impossible with this knowledge to decrypt the communication.The system does not rely on any secret information or hardware in any ofthe two modules, making this algorithm very well suited for thisapplication. For this technique to be integrated in both systems, aclose cooperation between car manufacturers and the telematica moduleengineers is required.

While the multiplexed bus is the most important issue in interfacingwith the vehicle, there probably remain specific input outputrequirements that can not be dealt with by means of the multiplexed bus.For these cases, the general input and output ports form an alternative.These ports can close and open contacts and can sense the state oftransducers. Their specific use is customized for a specific model of avehicle.

The method of the invention uses existing pan European networks with theguarantee that it can provide a European coverage of its services.

The method of the invention uses existing and standardizedinfrastructure which makes it an inherently more cost effectiveapproach. When new infrastructure is required, like the CDMA transceiverbeacons, the cost of this infrastructure is very small compared to therevenue that is generated with these beacons, i.e. the toll. However,the CDMA transceiver beacons are not limited to this toll application.

The communication in the vehicle itself is completely secured by aDiffie-Hellman key exchange algorithm as disclosed in theabove-mentioned publication “The First Ten Years of Public-KeyCryptography”.

Probably the most important difference between the method of theinvention and the prior art methods, is that the method of the inventionis not bound by a single application. The complete system is builtaround the concept of safe communication that is safe and secure,reliable, and cost effective.

This feature makes the invention stand out above all other systems sinceit provides a flexible platform for a whole slew of telematicaapplications.

The connection via the telephone network 2 is not permanent, so thatthis network is not overloaded.

Localization is very simple and accurate.

What is claimed is:
 1. A method for communicating with an object,comprising the steps of coupling a module with at least a transmitterand a receiver to the object, said module being one of a plurality ofmodules arranged to communicate with at least three communicationsnetworks, a first network being a wide area paging network with whichthe module selectively communicates, a second network being a cellularmobile communication network with which the module selectivelycommunicates and a third network being a local network which uses alocal beacon to communicate with all modules of said plurality ofmodules that pass nearby using a spread spectrum modulation method. 2.The method according to claim 1, further comprising the steps of sendinga signal over one of the three networks to the module and automaticallytransmitting a reply signal back over one of the three networks.
 3. Themethod according to claim 2, further comprising the steps of sending asignal over the paging network to the module and causing the module toautomatically transmit a reply signal back over the cellular mobilecommunications network the cellular mobile communication network beingswitched off during stand-by operation to guarantee privacy of thevehicle during the stand-by operation.
 4. The method according to claim2, further comprising the steps of causing the module to transmit backthe reply signal and using the reply signal for identification of theobject.
 5. The method according to claim 1, wherein the communicationpaging network is the European Radio Message System (ERMES).
 6. Themethod according to claim 1, wherein the cellular mobile communicationsnetwork is the Global System for Mobile (GSM) communications network. 7.A method according to claim 1, wherein said object is a vehicle, andfurther comprising the steps of using the wide area paging network forlarge volume communications and using the cellular mobile communicationsnetwork for bidirectional data communication towards and from thevehicle.
 8. The method according to claim 1, wherein the third networkis a Code Division Multiple Access (CDMA) network.
 9. A method accordingto claim 1, further comprising the step of using a third network whichcomprises a receiver used to receive data from a nearby said localbeacon and a transmitter used to send data to a nearby receiver, wherebyspreading codes of transmitters of several modules are different toenable a receiving beacon to recognize and differentiate data comingfrom each receiver that is a member of the population of receivers in avicinity of the beacon.
 10. The method according to claim 1, wherein thecommunication is used for the localization of a module.
 11. The methodaccording to claim 10, wherein information used to correlate towards alocalization of a module includes: timing information inherent to acellular mobile communications network protocol which is available tothe module and which is sent back to a service center, the timinginformation being correlated towards a distance from network basestations; and field strength and identity of a paging network basestation recorded at a moment where the timing information is extractedout of the mobile communications network, the strength being correlatedtowards a distance from the paging network base station in a vicinity ofthe module.
 12. The method according to claim 1, wherein the signalsfrom or to at least one of the communication networks are coded.
 13. Themethod according to claim 1, wherein the signals from or to at least oneof the communication networks is cryptographically transformed.
 14. Amethod according to claim 1, wherein interfaces between the module andsaid networks are controlled by a control module.
 15. The methodaccording to claim 14, wherein said object is a vehicle, and furthercomprising the step of using a control module which comprises aninterface with the vehicle.
 16. A method according to claim 15, furthercomprising the step of using a control module comprising an interfacewhich uses a cryptographic transformation for both authentication anddata security in communication with the electrical system of thevehicle.
 17. A method according to claim 1, wherein the data from or toat least one of the communication networks are digitally signed forauthorization.
 18. The method according to claim 1, further comprisingthe step of using a public key and a private key to make a cryptographictransformation of the signal transmitted over the paging network and fordecrypting the signal received over the cellular mobile communicationsnetwork.
 19. The method according to claim 1, further comprising thestep of downloading software by means of a receiving interface in saidmodule.
 20. The method according to claim 5, wherein the cellular mobilecommunications network is the Global System for Mobile (GSM)communications network.
 21. An apparatus for communicating with anobject comprising: a module mounted on an object to be communicatedwith, said module including: an interface with a paging network; aninterface with a cellular mobile communications network; and aninterface with a third local network using a spread spectrum modulationmethod.
 22. The apparatus according to claim 21, wherein the interfacewith the third local network is an interface with a network using theCode Division Multiple Access (CDMA) method.
 23. The apparatus accordingto claim 22, wherein the interface with the third network comprises aCDMA transmitter interface and a CDMA receiver interface.
 24. Theapparatus according to claim 21, further comprising a control module forcontrolling said interfaces.